1. Field of the Invention
The invention relates to a switch, more particularly to a vibration switch.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional vibration switch, as disclosed by the applicant in Taiwanese Patent No. 181432, includes a casting 10, a biasing member 20, a first electrode 30, and a moving element 40.
The casing 10 defines a chamber 13, and includes first and second casing parts 11, 12. The first casing part 11 is made of a conductive material, and has a first inner wall face 111, a first outer wall face 112, and a second electrode 113 projecting outwardly from the first outer wall face 112. The second casing part 12 is made of an insulating material, and has a second inner wall face 121 spaced apart from the first inner wall face 111, and a second outer wall face 122. A metal piece 123 is provided on the second inner wall face 121, and is connected electrically to the first casing part 11.
The biasing member 20 is a compression spring disposed in the chamber 13 and in contact with the metal piece 123.
The first electrode 30 is a conductive rod having one end inserted into the chamber 13 through the second outer and inner wall faces 122, 121. The metal piece 123 has a central through hole for extension of the first electrode 30 therethrough so that the metal piece 123 and the first electrode 30 are not connected electrically.
The moving element 40 is configured as a metal ball that is disposed movably in the chamber 13. When no external force is received by the conventional vibration switch, the moving element 40 abuts against the first inner wall face 111 through a biasing action of the biasing member 20 so that the moving element 40 is spaced apart from the first electrode 30.
When the conventional vibration switch is vibrated, the moving element 40 is displaced to thereby compress the biasing member 20 against the metal piece 123, so that the moving element 40 can connect electrically the first electrode 30 to the first casing part 11 through the biasing member 20 and the metal piece 123. When the moving element 40 is separated from the first electrode 30 by a restoring force of the biasing member 20, electrical connection between the first electrode 30 and the first casing part 11 is cut.
However, since the moving element 40 is not connected fixedly to the biasing member 20, and since the biasing member 20 is not connected fixedly to the metal piece 123, electrical connection between the first electrode 30 and the first casing part 11 is achieved through electrical contact points 101 between the first electrode 30 and the moving element 40, between the moving element 40 and the biasing member 20, and between the biasing member 20 and the first casing part 11. Since electrical connection of the conventional vibration switch is achieved through these three contact points 101, not only are unstable signals generated during use, but also electrical connection must occur at each of these three contact points 101 in order to achieve electrical connection between the first electrode 70 and the first casing part 11, thereby adversely affecting sensitivity of the conventional vibration switch.